The present invention is generally directed to processes for generating terahertz radiation, more specifically, the present invention is directed to, in embodiments, to providing processes for producing terahertz radiation from lasing of magnetic particles having long lived metastable states at non-zero magnetic fields, and providing imaging processes comprising lasing the aforementioned magnetic particle composition and exposing an object, for example, a two or three dimensional image, to the terahertz radiation arising therefrom, thereby transforming the incident terahertz radiation into a resultant terahertz specular beam containing two or three dimensional image content, and thereafter processing the terahertz beam to extract and record the two or three dimensional image content therefrom. In other embodiments, the present invention provides processes for high density, high resolution imaging and image recording media, and processes thereof.